principles of development (12-1)

Question 1

development (4 phases)

Answer 1

1. determination
2. differentiation
3. growth
4. morphogenesis

Question 2

2 types of development

Answer 2

1. direct development
2. indirect development

Question 3

characteristics of direct development (5 main ideas)

Answer 3

-newborn is miniature
-sexually immature
-no change in body form therefore only needs to grow
-needs much more nourishment before being born
-relatively few offspring produced at a time bc it requires more effort and more demand from mother (bc of much needed nourishment a growing embryo)

Question 4

how are food requirements met for the embryo? (both direct and indirect))

Answer 4

direct: either eggs conain large amounts of yolk, or little yolk and nourished within the body of the mother

indirect: numerous smaller eggs with relatively little yolk.

Question 5

characteristics of indirect development (5 main ideas)

Answer 5

-juveniles differ significantly from adults
-radical changes in body form
-larval stage is much smaller than juvenile of any directly developing species
-larvae are sexually immature, undergo metamorphosis
-many offspring produced

Question 6

major difference between indirect and direct development?

Answer 6

direct are mini versions of the adults. indirect involves larva hatching from egg which undergoes metamorphosis to an adult

Question 7

compare number of offspring

Answer 7

direct results in fewer offspring at a time bc of the effort required during embryonic development
indirect can produce many offspring at once since they produce small eggs with little yolk

Question 8

3 differences in development in protosomes and deuterostomes

Answer 8

1. cleavage (spiral/radial & determinante/indeterminate)
   2.coelom (pinches off from gut/solid mesoderm splits)
2. blastopore (varies in anus or mouth forming first)

Question 9

cytoplasmic determinants

Answer 9

molecules that regulate gene expression. when cleavage occurs cells become differentiated therefore location of cell dtermines its destiny. (cells are still genetically identical)

Question 10

morula

Answer 10

embryo has not grown in size, just cells have divided to make more. not hollow yet.

Question 11

blastulation

Answer 11

morula–>blatula

forms a cavity called blastocoel. can tell cells apart now. cells on outside are trophoblast and the mass formed is the embryoblast.

at this stage it implants into uterine wall!!

single layered!!!

Question 12

blastocyst

Answer 12

only mammalian blastulas called this

Question 13

gastrulation

Answer 13

1 layered blastula–> 3 layered gastrula

1.cells of inner mass (embryoblast) forms a cavity, the amniotic cavity. then the cells under differentiate into epiblast and hypoblast.

2. epiblast cells go inwards forming primitive streak (marks arrangement of cells that will migrate inwards forming 3 germ layers) and forms blastopore. (GRASTRULASTION STARTS HERE)
3. then forms germs layers ectoderm, mesoderm, endoderm.

Question 14

invagination

Answer 14

process in gastrulation. folding inwards to form 3 layers, primitive streak and blastopore???

Question 15

at what point does gastrulation begin

Answer 15

when cells brgin to migrate inward. blastopore and primitive streak

Question 16

coelom formation

Answer 16

coelom=body cavity located between digestive tract & outer body wall

forms differently in p&d
p: solid mesoderm splits
d: mesoderm pockets pinch from gut

Question 17

archenteron

Answer 17

early gut cavity

Question 18

blastopore

Answer 18

becomes mouth and then anus in protosomes

anus and then mouth in deuterostomes

Question 19

protosomes v and deutersotomes include…

Answer 19

p: segmented worms, mollusks, insects, spiders & arthroppods

d: echinoderms, chordates

Question 20

neuralation

Answer 20

last step

1. notochord in the middle of the mesoderm induces change in ectoderm (thickens it) which forms neural plate
2. neural tube forms as neural plate divides mesoderm and forms ring like structure (notochord dot bcomes a hollow tube which is the neuaral tube)

Question 21

where does each stage occur in humans

Answer 21

fertilization and cleavage in fallopian tubes. blastula implants in uterine wall

Question 22

modified amniotic egg (humans)

Answer 22

outer layer of blastocysts expands into endometrium (=inner layer of uterus). and four new extraembryonic membranes appear

1. chorion
2. amnion
   3.allantios
3. yolk sac

they provide more complex life support for embryos of animals that live on land and have terrestrial life constraints

Question 23

chorion

Answer 23

helps exchange gasses between embryo and environment

choro causes gas

Question 24

amnion

Answer 24

protects embryo in fluid-filled cavity that cushions against mechanical shock

amneet is super protective

Question 25

allantois

Answer 25

disposal sac for embryos matabolic waste

french and french are garbage tehrefore disposal for metabolic waste

Question 26

yolk sac

Answer 26

storage of nutrients